cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A010571 High temperature expansion of -u/J in odd powers of v = tanh(J/kT), where u is energy per site of the spin-1/2 Ising model on cubic lattice with nearest-neighbor interaction J at temperature T.

Original entry on oeis.org

3, 12, 120, 1368, 18300, 268728, 4179852, 67767744, 1133826324, 19443072084, 340085761968, 6046276240668, 108970501777080, 1986820814551056, 36587507853481908, 679619087721892176, 12720247240214281860, 239685390231729125004, 4543441582487318876664
Offset: 1

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Crossrefs

Formula

Sum_{n>=1} a(n) * v^(2*n-1) = v*q/2 + (1-v^2) * f'(v) / f(v), where f(v) = Sum_{n>=0} A001393(n) * v^(2*n) and q = 6 is the number of nearest neighbors. - Andrey Zabolotskiy, Feb 14 2022

Extensions

New name from Andrey Zabolotskiy, Jan 14 2019
a(7) corrected and more terms added by Andrey Zabolotskiy, Feb 14 2022

A002908 High temperature expansion of -u/J in odd powers of v = tanh(J/kT), where u is energy per site of the spin-1/2 Ising model on square lattice with nearest-neighbor interaction J at temperature T.

Original entry on oeis.org

2, 4, 8, 24, 84, 328, 1372, 6024, 27412, 128228, 613160, 2985116, 14751592, 73825416, 373488764, 1907334616, 9820757380, 50934592820, 265877371160, 1395907472968, 7366966846564, 39062802311672, 208015460898924, 1112050252939612, 5966352507546872
Offset: 1

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Comments

Previous name was: Energy function for square lattice.

References

  • C. Domb, Ising model, in Phase Transitions and Critical Phenomena, vol. 3, ed. C. Domb and M. S. Green, Academic Press, 1974; p. 386.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    series((1+v^2)*(1-(2/Pi)*(1-6*v^2+v^4)*EllipticK(4*v*(1-v^2)/(1+v^2)^2)/(1+v^2)^2)/2*v,v,50); # Sean A. Irvine, Nov 26 2017
  • Mathematica
    u[h_]:=Coth[2h](1+(2/Pi)(2Tanh[2h]^2-1)EllipticK[(2Sinh[2h]/Cosh[2h]^2)^2]);
    Table[SeriesCoefficient[u[ArcTanh[v]],{v,0,2n-1}],{n,10}]
    (* Andrey Zabolotskiy, Sep 12 2017; see Onsager's eq. (116) *)
    Rest[CoefficientList[Series[(1+x)/2 - (1 - 6*x + x^2)*EllipticK[(16*(-1 + x)^2*x)/(1 + x)^4] / (Pi*(1+x)), {x, 0, 25}], x]] (* Vaclav Kotesovec, Apr 27 2024 *)

Formula

a(n) ~ 2 * (1 + sqrt(2))^(2*n-1) / (Pi * n^2). - Vaclav Kotesovec, Apr 27 2024

Extensions

More terms and new name from Andrey Zabolotskiy, Oct 19 2017

A010557 Fourth-field derivative of Ising model free energy for 4-d cubic lattice.

Original entry on oeis.org

1, 32, 584, 8288, 101240, 1121120, 11570360, 113293088, 1064631032, 9681082144, 85688330696, 741562925664, 6296196525768, 52589092312288, 433044168426616, 3521747918221984, 28326976016327032, 225625290109912096, 1781402824552864712, 13954143265951219296, 108525895871787179576
Offset: 0

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Extensions

Name clarified, a(17)-a(20) using Butera & Pernici's formulas added by Andrey Zabolotskiy, Nov 25 2024

A010563 High-temperature expansion for Ising model spin-spin correlation function on 4-d cubic lattice.

Original entry on oeis.org

1, 6, 108, 2628, 72638, 2200108, 71072290, 2405434612
Offset: 0

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Crossrefs

Cf. A010572, A030044 (partition function), A010557 (fourth-field derivative of free energy); A010564 ("HBCC" lattice), A010565 (D_4 lattice).

Formula

a(n) = A010572(n) / 4. - Andrey Zabolotskiy, Nov 19 2024

Extensions

Name clarified and terms a(6)-a(7) using data from A010572 added by Andrey Zabolotskiy, Nov 25 2024
Showing 1-4 of 4 results.